Investigation of parameters of submicron porosity of WWER fuel pellets

In order to provide competitive ability of Russian fuel on the world market it is necessary to control the pore distribution on submicron level. This problem is a result of burning depth requirement that is related to holding fission gases inside of the fuel pellet. According to modeling results share of submicron pores in intragranular pores is sufficient and plays leading part in capturing fission gases inside the pellet. This paper provides a method of determination of submicron porosity parameters and its distribution over uranium dioxide fuel pellet. Submicron porosity research was carried out on samples made of various powder types and method of manufacturing. As a result distribution of submicron porosity over nuclear fuel pellet is presented. Theory of submicron pores formation is offered. (authors)